Question

A spherical convex surface of radius of curvature $20cm$,made of glass $(\mu =1.5)$ is placed in air. find the position of the image formed , if a point object is placed at $30cm$ in front of the convex surface on the principal axis.

Answer 1

$\frac{h_2}{v}-\frac{h_1}{u}=\frac{h_2-h_1}{R}$

Putting $h_2=1.5,h_1=1$

$u=-30cm.R=+20cm$

So we get

$\frac{1.5}{v}-\frac{1}{-30}=\frac{1.5-1}{20}=\frac{1}{40}$

$\Rightarrow \frac{1.5}{v}=\frac{1}{40}-\frac{1}{30}=\frac{3-4}{120}=\frac{-1}{120}$

$\Rightarrow v=-180cm$

i.e in the air side